Accumulator



L. N. ASCARI ACCUMULATOR Filed May 29, 1936 lA/VE/VTOT? Patented Oct. 17, 1939 UNITED STATES PATENT OFFICE Application May 29, 1936, Serial No. 82,648 In Italy June 3, 1935 3 Claims.

This invention relates to accumulators, and more particularly to the manufacture of accumulators from plates which are produced according to a certain method and on the relative arrangement of which there also depends the selection of the electrolyte.

According to the invention, there are employed for the anode and for the cathode or merely for the anode alone flat plates which are produced by pouring a metal alloy, which serves to form the active material, in a liquid condition into fields or divisions of the grid. In these fields projections furnished along the inner edge project into the said alloy.

The metal alloy forming the active material is united with the grid or other conductor or support in a mold, the metal being poured in whilst sealing is effected by means of an inert gas which fills out the crucible and the mold.

The temperature and the discharge of the heat in respect of the plate mold are such that the metal alloy solidifies after complete filling of the mold, without a grid or other support previously introduced into the mold, even if the same has a'lower melting point than the metal alloy, being caused to fuse by reason thereof or to vary its condition chemically or mechanically. The electrode plate is produced by the fact that the mold is made to communicate in direct fashion with a rotatable crucible. The mold or the molds are filled'upon each revolution and are opened or closed in rhythm.

Prior to removal of the grids filled out with the metal alloy apertures may be pierced therein by means of pins which at the same time remove the casting heads.

'If the plates aforesaid are employed in the accumulator only for the anode, there is employed for the cathode a Zinc alloy. The electrolyte then consists of aqueous sulphuric acid and zinc sulphate and also a catalytic addition of metallic mercury, which prevents. or retards crystallisation of the zinc sulphate.

I There is employed for the accumulator a box or 45 jar of the kind known per se composed of glass, cellulose derivatives or the like, and the number of the plates and also their dimensions will depend on. the electrical requirements.

The production of the plates as described in the above preferably takes place by means of a casting machine in continuous operation.

A form of embodiment of a casting machine suitable for the purpose of the invention is illustrated diagrammatically by Way of example in the accompanying drawing, in which Fig. 1 is an elevational view of the melting and casting crucible adapted to rotate about a shaft.

Fig. 2 shows a crucible with casting means in the position of removal.

Fig. 3 shows the casting machine with the crucible rotated to the extent of approximately as compared with Fig. 2.

Fig. 4 is a section through part of the crucible showing the means for producing the apertures in the finished plates.

Fig. 5 is a view similar to Fig. 4, but with the piercing members in the retracted position.

Fig. 6 is a plan view of a possible form of embodiment of a finished plate, and

Fig. '7 is a part view in plan of a grid employed for producing the plate according to Fig. 6.

The grid of the plate consists of a desired metal or other suitable material. At the present time it is usual to employ the known lead compounds. The grid fields or divisions are filled out with an alloy of lead and alkaline metal, preferably with lead-sodium, for producing spongy lead, or with a similar alloy which is capable of activation.

The metal alloy poured into the fields or divisions of the grid in liquid state completely fills out these fields, undesirable oxidation being extensively precluded by the fact that the crucible and the mold are filled with an inert gas under pressure. The crucible in the form of embodiment illustrated in the drawing is constructed as a rotatable chamber l. furnished with gasheating or electrical heating means 2. Projections or other auxiliary means 3 ensure an extensive mixing of the alloy.

The crucible rotates about a shaft l, which may be employed for supplying the inert gas or also for the continuous supply of the alloy. The heating current may be supplied by means of wiping contacts 5. There is provided in immediate connection with the crucible l the casting device or mold comprising the base plate 6 and the bottom plate 1. The parts of the mold are held together by the lever mechanism 8.

In producing the plates a prepared grid is placed between the mold sections 6 and l. The mold is then closed and the crucible l rotated in the direction of the arrow inFig. 2 or 3, the alloy thereupon passing into the mold through the apertures 9 (Fig. 5). A packing or suitable heat-insulating means I0 is provided between mold and crucible.

The grid, which has now been completely filled out with the alloy employed to form the active material, is removed by opening the mold 6, I. The opening and closing of the mold takes place configurations on the plate.

as a rhythmical function in the rotation of the crucible l, in which connection mechanical or electrical control means may be furnished for the opening and closing of the mold G, 1, 8 in the proper positions of the crucible. There may also be provided a plurality of plate molds in association with one crucible, in which case it will be necessary to ensure that the alloy introduced into the molds is adequately mixed. The molds, of course, are not limited to the specific embodiment comprising the two plates shown in the drawing.

Provision is made for regulation of the temperature and discharge of the heat in respect of the mold or molds during the process of manufacture. For this purpose the mold itself may be so constructed for the discharge of heat by the provision of fins, heating means, cooling passages or the like that the metal alloy introduced through the apertures 9 into the mold scavenged by the inert gas fills out all corners of the mold in rapid and complete fashion and solidifies as quickly as possible. At the same time the grid which is placed in the mold and usually possesses a lower melting point than the metal alloy is not caused to melt. The condition of the grid is also in no way varied either mechanically or chemically. Naturally in place of the grid other supporting means having a lower melting point than the metal alloy may also be coated or united with the latter.

Owing to the, described embodiment of and method of manipulating the mold by immediate contact and owing to the fact that the grid rests against a continuous surface having a large area the walls of the mold discharge the heat of the liquid metal alloy partly direct and partly by way of the grid, so that the latter does not undergo any appreciable increase in temperature. Thus, for example, the temperature of the mold may be 200 C., the melting point of the grid 327 C., and the temperature of the metal alloy upon its introduction approximately 380 C. without damage to or any undesirable attack on the grid.

It is possible in accordance with the invention to produce not only flat plates, but also cylindrical or other forms.

. The mold 6, I is conveniently furnished on the inside with grooves, which are filled out when the metal is poured in and form corresponding At the same time these grooves serve for the discharge of the inert gas upon the introduction of the metal.

The inlet aperture 9 in the mold plate 6 and also correspondingly large borings in the plate 1 act as guides for pins II, by means of which apertures are produced in the castplate, preferably immediately prior to the complete solidifying of the plate. The pins II, which are mounted on a common plate I 2 (Figs. 4 and 5) and may be advanced and withdrawn together with the same, pass through the openings in the plate I, penetrate the fields or divisions of the plate filled out with alloy, pass through the openings 9 in the base plate 6 and eject the dead heads from these openings, the heads being returned to the bath.

Upon the return of the pins II the openings 9 are again uncovered. The control of the pins II, or the base plate l2 respectively, may take place by.means of a stop l3, which acts by way of a lever mechanism [4 on a rack and pinion gear l5.

The dimensions of the plate and the grid will depend on the electrical requirements. The fields or divisions [6 of the plate are preferably smaller towards the poles H. In the fields [6 there are provided along the edges in the plane of the plate projections 18 which extend into the active material, hold the latter and ensure a good passage of the current. The projections l8 may be pressed or cast integrally or produced otherwise in desired fashion.

As shown in Fig. 6, the grid is still to be recognised in the finished plate filled out with the active material, so that each field I6 is complete in itself. The openings [9 in the fields or divisions of the grid produced by the pins H may be provided in desired number.

Whereas in the preferred form of embodiment of the accumulator produced in accordance with the invention the anode plates and the cathode plates are produced according to the same process from the same materials, it is also possible to employ for the cathodes plates consisting of a zinc alloy, for which piu'pose an alloy comprising approximately zinc and copper with traces of cobalt and tin has been found to be particularly suitable.

Whereas in the first embodiment aqueous sulphuric acid is employed as electrolyte, there is preferably used in the case of the zinc cathode an electrolyte consisting of aqueous sulphuric acid and zinc sulphate containing a catalytic addition of metallic mercury. There may also be added to the electrolyte sulphates of mercury, of which the one (HgSO42(I-Ig0 is water-soluble in the electrolyte, and the other (HgSOi) is not. Whilst the addition of the sulphates of mercury, owing to amalgamation, facilitates the re- Versible decomposition of the Zinc and renders the same more uniform in nature, the metallic mercury has the object of preventing or retarding crystallisation of the zinc sulphate.

The electrode plates according to the invention are extremely homogeneous, light in weight, very resistant, readily capable of extreme re-crystallisation, are durable, insensitive to fluctuations in the current and in charging, and provide a higher medium voltage than the plates hitherto in use. They may be produced rapidly and in simple fashion, but at the same time comply with all mechanical requirements. The process of manufacture may be united in the casting operation, the filling of all fields or divisions taking place simultaneously or in immediate succession being immediately followed by production of the apertures IQ for example in one revolution of the crucible l.

It will be obvious that numerous modifications are quite possible within the meaning of the above description and the annexed claims without departing from the spirit of the invention.

What I claim as new and desire to secure by Letters Patent is: v

1. The method of producing accumulator plates comprising placing in a mould a pre-cast grid of low melting point divided into fields by bars each having at least two surfaces in close contact with the mould, introducing directly into each field from a crucible a stream of molten metal of at least 50 0. higher melting point than the grid and adapted for transformation into active material, filling each field, piercing the said metal in each field and fully removing all of each deadhead simultaneously and finally removing the finishedplate from the mould.

2. The method of producing accumulator plates, which consists in placing in a mould a low melting point grid' divided into independent fields, fusing in a crucible directly connected with but insulated from said mould a metal of at least 50 C. higher melting point than said grid, and adapted for transformation into active material, introducing the said metal into said mould in a separate stream directly from the crucible for each field, allowing the metal to partially set, piercing the metal in each field and returning the complete deadheads simultaneously to the crucible, and removing the finished plate from the mould when fully set.

3. The method of producing accumulator plates comprising placing in a mould having a temperature approximately 200 C. a pre-cast grid having a melting point of approximately 325 C. and

divided into independent fields by integral bars each having substantial contact area with the mould, introducing directly into each field through an opening in the mould wall a separate stream of molten alloy having a melting point of approximately 375 C. and adapted for transformation into active material, the mass and temperature of the mould causing the alloy to set with sufficient rapidity to prevent melting of or alloying with the grid, piercing each field in alignment with said mould opening and simultaneously driving the complete deadheads out through said openings so as to leave no sprues on the finished casting.

LUI'A N'ELUSCO ASCARI. 

